The present invention relates to a sealing system for use in cooling a roller, and in particular, to a device for connection of a coolant feed to a roller for continuous casting plants.
Rotatable lead-throughs are required in different branches of industry, especially for continuous casting plants in the steel industry. In these continuous casting plants, the red-hot steel runs in the form of billets over rollers, which are rotatably mounted externally in bearings in bearing blocks. These rollers are cooled in a closed circulation by admission of water under pressure into the interior of the rollers to dissipate heat. The rotatable lead-through seals the transition from the so-called rotor and the cooling water line flange-mounted thereon to the housing secured to the roller and co-rotating with it.
Essentially, two different types of rotatable lead-through are known in the art. A first construction of the rotatable lead-throughs comprises a structural unit lying outside the roller interior, which contains the elements for the necessary water supply, mounting and sealing. Depending on the construction, installations of that kind having such rotatable lead-throughs have a considerable width to the right and left of the bearing blocks.
To reduce the installation width, some system manufacturers have moved the bearing and sealing system to the inside of the roller.
To receive the rotatable lead-through in the roller, a bore is provided, into which the rotatable lead-through is inserted and then fixedly connected, for example, by way of a screwed connection, to the roller. The water used for cooling is introduced into the rotatable lead-through at a pressure of up to about 15 atmospheres above atmospheric pressure, and the water pressure acting on the components, together with the movement of the same and the thermal stress, places heavy demands on the sealing technology.
A technique used to seal the components of the rotatable lead-through moving relative to one another as the roller rotates is based on the use of a radial seal consisting of circular O-rings or lip seals of elastomer as the crucial sealing element.
Other techniques are described in EP-A1-392 838. This publication describes a rotatable lead-through with a sealing arrangement that is operated by the hydraulic pressure of the fluid. This is, however, a structurally complex arrangement.
An attribute common to the rotatable lead-throughs known in the art is that, especially when the roller is subjected to radial loadings, because of the relatively rigid water supply and discharge lines, shearing forces act on the rotatable lead-throughs and cause considerable wear to the rotatable lead-through. An added factor is the mostly complicated mechanical construction of the rotatable lead-throughs known in the art.
It is therefore desired to provide a wear-resistant lead-through, which permits a reliable operation combined with an extended service life, that is of simple construction and, in the case of continuous casting installations currently in use, can be used as an exchangeable component without modification to the installation itself.